Particle detection in superfluid helium
In this thesis, results are presented for a prototype solar neutrino detector which uses superfluid helium as a target. The prototype consists of a 3 liter helium target maintained at 40 mK by a dilution refrigerator, and a low mass calorimeter suspended above the liquid surface. An {sup 241}Am film immersed in the helium provides 5.5 MeV {alpha} particles which are detected in the experiment. In the detection process, the {alpha} particle deposits a fraction of its energy in rotons and phonons which travel ballistically in the liquid at low temperatures. The excitations which reach the free surface have a finite probability of evaporating helium atoms from the surface and the evaporation signal is detected by the calorimeter mounted above the liquid. The experimental results show that the {alpha} particle deposits a substantial fraction of its energy in the liquid producing predominantly rotons with momentum near the roton minimum of the dispersion curve (1.91 {angstrom}{sup {minus}1}). In addition, the evaporation signal produced by the rotons has been observed and is shown to be peaked directly above the {alpha} source in the detector. The results also indicate that the magnitude of the evaporation signal depends on both the energy and the initial direction of the {alpha} particle stopped in the helium target. Finally, these results are compared to Monte Carlo simulations and the implications for a full scale detector are discussed.
- Research Organization:
- Brown Univ., Providence, RI (United States). Dept. of Physics
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-88ER40452
- OSTI ID:
- 10122407
- Report Number(s):
- DOE/ER/40452-10; ON: DE94006547; BR: KB0401000; TRN: AHC29404%%76
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: May 1994
- Country of Publication:
- United States
- Language:
- English
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